US20080026654A1 - Exhaust device for outboard motor - Google Patents
Exhaust device for outboard motor Download PDFInfo
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- US20080026654A1 US20080026654A1 US11/829,499 US82949907A US2008026654A1 US 20080026654 A1 US20080026654 A1 US 20080026654A1 US 82949907 A US82949907 A US 82949907A US 2008026654 A1 US2008026654 A1 US 2008026654A1
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- Prior art keywords
- exhaust
- cylinders
- case
- outboard motor
- partition
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Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N13/00—Exhaust or silencing apparatus characterised by constructional features ; Exhaust or silencing apparatus, or parts thereof, having pertinent characteristics not provided for in, or of interest apart from, groups F01N1/00 - F01N5/00, F01N9/00, F01N11/00
- F01N13/08—Other arrangements or adaptations of exhaust conduits
- F01N13/10—Other arrangements or adaptations of exhaust conduits of exhaust manifolds
- F01N13/107—More than one exhaust manifold or exhaust collector
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N13/00—Exhaust or silencing apparatus characterised by constructional features ; Exhaust or silencing apparatus, or parts thereof, having pertinent characteristics not provided for in, or of interest apart from, groups F01N1/00 - F01N5/00, F01N9/00, F01N11/00
- F01N13/004—Exhaust or silencing apparatus characterised by constructional features ; Exhaust or silencing apparatus, or parts thereof, having pertinent characteristics not provided for in, or of interest apart from, groups F01N1/00 - F01N5/00, F01N9/00, F01N11/00 specially adapted for marine propulsion, i.e. for receiving simultaneously engine exhaust gases and engine cooling water
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N13/00—Exhaust or silencing apparatus characterised by constructional features ; Exhaust or silencing apparatus, or parts thereof, having pertinent characteristics not provided for in, or of interest apart from, groups F01N1/00 - F01N5/00, F01N9/00, F01N11/00
- F01N13/08—Other arrangements or adaptations of exhaust conduits
- F01N13/085—Other arrangements or adaptations of exhaust conduits having means preventing foreign matter from entering exhaust conduit
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N13/00—Exhaust or silencing apparatus characterised by constructional features ; Exhaust or silencing apparatus, or parts thereof, having pertinent characteristics not provided for in, or of interest apart from, groups F01N1/00 - F01N5/00, F01N9/00, F01N11/00
- F01N13/12—Exhaust or silencing apparatus characterised by constructional features ; Exhaust or silencing apparatus, or parts thereof, having pertinent characteristics not provided for in, or of interest apart from, groups F01N1/00 - F01N5/00, F01N9/00, F01N11/00 specially adapted for submerged exhausting
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N13/00—Exhaust or silencing apparatus characterised by constructional features ; Exhaust or silencing apparatus, or parts thereof, having pertinent characteristics not provided for in, or of interest apart from, groups F01N1/00 - F01N5/00, F01N9/00, F01N11/00
- F01N13/001—Gas flow channels or gas chambers being at least partly formed in the structural parts of the engine or machine
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N13/00—Exhaust or silencing apparatus characterised by constructional features ; Exhaust or silencing apparatus, or parts thereof, having pertinent characteristics not provided for in, or of interest apart from, groups F01N1/00 - F01N5/00, F01N9/00, F01N11/00
- F01N13/08—Other arrangements or adaptations of exhaust conduits
- F01N13/10—Other arrangements or adaptations of exhaust conduits of exhaust manifolds
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N2240/00—Combination or association of two or more different exhaust treating devices, or of at least one such device with an auxiliary device, not covered by indexing codes F01N2230/00 or F01N2250/00, one of the devices being
- F01N2240/36—Combination or association of two or more different exhaust treating devices, or of at least one such device with an auxiliary device, not covered by indexing codes F01N2230/00 or F01N2250/00, one of the devices being an exhaust flap
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N2590/00—Exhaust or silencing apparatus adapted to particular use, e.g. for military applications, airplanes, submarines
- F01N2590/02—Exhaust or silencing apparatus adapted to particular use, e.g. for military applications, airplanes, submarines for marine vessels or naval applications
- F01N2590/021—Exhaust or silencing apparatus adapted to particular use, e.g. for military applications, airplanes, submarines for marine vessels or naval applications for outboard engines
Definitions
- the present inventions relate to exhaust devices, for example, exhaust devices that can be used for outboard motors which can reduce or prevent mutual interference of exhaust pulses from a plurality of cylinders of an engine.
- Japanese Patent Document JP-A-2000-265836 discloses a known exhaust device of a multicylinder engine.
- one set of exhaust passages extending respectively from a plurality of cylinders subjected to odd-numbered ignitions are joined at a point to form a first joined passage and another set of exhaust passages extending respectively from a plurality of cylinders subjected to even-numbered ignitions are joined at another point to form a second joined passage.
- These joined passages are further joined at another point into single consolidated exhaust passage.
- the downstream end of the consolidated exhaust passage communicates with the ambient atmosphere.
- the engine described in Japanese Patent Document JP-A-2000-265836 is used as a drive source for an outboard motor. It is generally desirable to make the engines of outboard motors as small as possible to reduce the aerodynamic drag created by the outboard motor, as well as for other reasons. To make such engines more compact, the length of the exhaust passages can be shortened. In this case, the cylinders subjected to odd-numbered explosions, which occur prior, and the cylinders subjected to even-numbered explosions, which occur later and subsequently to the former, will be positioned in proximity to each other because of the length of the shortened exhaust passages described above.
- an exhaust device for an outboard motor can comprise an engine having a plurality of cylinders.
- a first expansion chamber case can be configured to collect therein exhaust from a first part of the plurality of cylinders.
- a second expansion chamber case can be configured to collect therein exhaust from a second part of the plurality of cylinders.
- First and second exhaust passages can extend individually from the first and second expansion chamber cases, respectively, each of the first and second exhaust passages can have a downstream end opening communicating with water.
- an outboard motor can comprise an engine having a plurality of cylinders.
- a case can include a lower portion configured to be submerged in water during operation of the outboard motor.
- a first expansion chamber case can be configured to collect therein exhaust from a first group of the plurality of cylinders.
- a second expansion chamber case can be configured to collect therein exhaust from a second group of the plurality of cylinders.
- First and second exhaust passages can extend individually from the first and second expansion chamber cases, respectively, each of the first and second exhaust passages having separate downstream end openings disposed on the lower portion.
- FIG. 1 is a schematic diagram generally illustrating an engine in accordance with an embodiment.
- FIG. 2 is a schematic side view of a rear part of a watercraft including an outboard motor which, in turn, can include the engine of FIG. 1 .
- FIG. 3 is a partial rear elevational view of a lower portion of the outboard motor.
- FIG. 4 is a cross-sectional view taken along the line IV-IV in FIG. 3 .
- FIG. 5 is a schematic side elevational view of the engine, with certain components of the exhaust system shown in phantom line.
- FIG. 6 is a rear elevational view of the engine with certain components of the exhaust system shown in phantom line.
- FIG. 7 is a partial bottom plan and schematic cross-sectional view of the engine.
- FIG. 8 is an enlarged detailed cross-sectional view of an exhaust port of the engine.
- FIG. 9 is a perspective view of a portion of an exhaust device.
- FIG. 10 is a plan and cross-sectional view of regulating parts and regulating valves that can be used with the exhaust device.
- FIG. 11 is a schematic side elevational view of a modification of the engine of FIGS. 1-10 , with certain components of the exhaust system shown in phantom line.
- FIG. 12 is a front view of the engine of FIG. 11 , with certain covers removed and certain components shown in phantom line.
- FIG. 13 is a top plan and partial cross-sectional view of the engine of FIG. 11 .
- FIG. 14 is an enlarged cross-sectional view of a portion of FIG. 11 .
- FIG. 15 is a schematic side elevational view of another modification of the engine of FIGS. 1-10 , with certain components of the exhaust system shown in phantom line.
- FIG. 16 is a front view of the engine of FIG. 15 .
- FIG. 17 is a plan view of a portion of the engine of FIG. 15 .
- FIG. 18 is a partial bottom plan and schematic cross-sectional view of the engine of FIG. 15 .
- FIG. 19 is a perspective view of a portion of the exhaust device that can be used with the exhaust system of the engine of FIG. 15 .
- FIG. 20 is an enlarged cross-sectional view of a portion of FIG. 17 .
- FIG. 21 is an enlarged cross-sectional view of another portion of FIG. 17 .
- FIG. 1 Improved exhaust systems for an engine 11 ( FIG. 1 ) are disclosed herein. Although the present exhaust systems are illustrated and described in the context of an outboard motor, certain aspects of the present inventions can be used with engines of other types of vehicles, as well as with other types of prime movers.
- an exhaust device for an outboard motor is configured to reduce or prevent mutual interference of exhausts from a plurality of cylinders of an engine of the outboard motor, thereby providing enhanced performance of the engine more reliably.
- an exhaust device for an outboard motor can include an engine having a plurality of cylinders.
- a first expansion chamber case can be configured to collect therein exhaust from a first part of the plurality of cylinders.
- a second expansion chamber case can also be configured to collect therein exhaust from a second part of the plurality of cylinders.
- First and second exhaust passages can extend individually from the first and second expansion chamber cases, respectively, and communicate with water at the downstream end openings.
- a small watercraft 1 ( FIG. 2 ) can be designed to float on the surface of water 2 such as the sea.
- the arrow Fr indicates the forward direction in which the watercraft 1 is driven.
- the term “left and right” used herein refers to the width direction of the watercraft 1 with respect to the above forward direction.
- the watercraft 1 can include a hull 3 designed to float on the surface of the water 2 , and an outboard motor 4 supported at the stern of the hull 3 .
- the outboard motor 4 can include an outboard motor body 5 for producing propulsive force to selectively drive the hull 3 forward or rearward, and a bracket 6 for supporting the outboard motor body 5 on the hull 3 .
- the outboard motor body 5 can include a case 9 , a propeller 10 , an engine 11 , a power transmission apparatus 12 and a cowling 13 .
- the case 9 can extend generally vertically, and can be supported on the hull 3 by the bracket 6 .
- a lower portion of the case 9 can be designed to be submerged in the water 2 .
- the propeller 10 is supported at the lower end of the case 9 .
- the engine 11 is supported at the upper end of the case 9 .
- the power transmission apparatus 12 is enclosed in the case 9 , and operatively connects the propeller 10 to the engine 11 .
- the cowling 13 selectively covers and uncovers the engine 11 on the outside thereof It should be noted that the “surface 2 a of the water 2” described above is the water level during the watercraft 1 being driven forward, and can fluctuate vertically to some degree.
- the power transmission apparatus 12 can include a gear switching device 14 for changing the driving state of the propeller 10 between a forward drive mode, a reverse drive mode and a neutral mode, through a user's manual operation.
- the operation of the switching device 14 allows the hull 3 to be selectively driven either forward or rearward, or to be allowed to drift, during operation of the engine 11 .
- the engine 11 is a four-stroke V-type engine having a plurality of (eight) cylinders, and is used as a drive source for the outboard motor 4 .
- this is merely one type of engine that can be used.
- the present exhaust systems and exhaust components can be used with any of a variety of engines having other numbers of cylinders, and/or other cylinder arrangements, and/or operating on other principles of operation (diesel, 2-stroke, rotary, etc.).
- the engine 11 includes an engine body 15 , an intake device 17 and an exhaust device 19 .
- the engine body 15 is supported on the top of the case 9 .
- the intake device 17 supplies a mixture of ambient air 16 and fuel to the engine body 15 .
- the exhaust device 19 discharges burnt gas resulting from combustion of the mixture in the engine body 15 to the outside of the engine 11 as exhaust 18 .
- the case 9 has an oil tank 20 having stored therein lubricant for lubricating various parts of the engine body 15 .
- the engine 11 can include an engine body 15 , an intake device 17 and an exhaust device 19 .
- the crankcase 23 can be supported on the top of the case 9 , and can support a crankshaft 22 for rotation about a vertical axis 21 .
- the left and right banks 24 and 25 project horizontally to the outside, or rearward and toward the sides, from the crankcase 23 in a V-configuration as viewed in the bottom view of the engine 11 ( FIG. 7 ).
- the angle made by the banks 24 , 25 specifically by first to eighth cylinders 27 A to 27 H, is approximately 60°.
- the first to eighth cylinders 27 A to 27 H are ignited sequentially in that order.
- one (left) bank 24 of the banks 24 , 25 can be formed by the first, fourth, sixth and seventh cylinders 27 A, 27 D, 27 F and 27 G.
- the cylinders 27 A, 27 D, 27 F, 27 G can be arranged in the downward direction in that order.
- the other (right) bank 25 can be formed by the eighth, third, fifth and second cylinders 27 H, 27 C, 27 E and 27 B.
- the cylinders 27 H, 27 C, 27 E, 27 B can be arranged in the downward direction in that order.
- the first to eighth cylinders 27 A to 27 H can be arranged in the downward direction in order of the first cylinder 27 A, the eighth cylinder 27 H, the fourth cylinder 27 D, the third cylinder 27 C, the sixth cylinder 27 F, the fifth cylinder 27 E, the seventh cylinder 27 G and the second cylinder 27 B.
- the crankshaft 22 can include a crank main shaft 30 , crank arms 31 and crankpins 32 .
- the crank main shaft 30 can be positioned about the axis 21 , and can have journals supported by the crankcase 23 .
- the crank arms 31 can project from the crank main shaft 30 .
- the crankpins 32 can be supported by the respective crank arms 31 , and associated respectively with the first to eighth cylinders 27 A to 27 H.
- the angle made by the banks 24 , 25 can be approximately 60° as described above.
- the eight crankpins 32 associated with the first to eighth cylinders 27 A to 27 H can be arranged in the following manner, as viewed in the bottom view of the engine 11 ( FIG. 7 ).
- crankpins 32 associated with the first, eighth, fourth, third, seventh, second, sixth and fifth cylinders can be arranged in that order in the counterclockwise direction of the crankshaft 22 .
- the angle made by the crankpins 32 associated with each pair of the first and eighth cylinders, the fourth and third cylinders, the seventh and second cylinders, and the sixth and fifth cylinders can be 30°.
- the angle made by the crankpins 32 associated with each pair of the eighth and fourth cylinders, the third and seventh cylinders, the second and sixth cylinders, and the fifth and first cylinders can be 60°. That is, the crankshaft 22 can be of similar type to that of so-called cross plane/double plane/dual plane crank type of a V-type, multicylinder engine having a bank angle of 90°.
- Each of first to eighth cylinders 27 A to 27 H can include a piston 35 and a connecting rod 36 .
- the piston 35 can be fitted in a cylinder bore 34 of each cylinder in a manner sliding axially therealong.
- the connecting rod 36 can operatively connect the piston 35 and the crankpin 32 of the crankshaft 22 .
- Each cylinder 27 can have intake and exhaust ports 38 and 39 for communicating the inside and the outside of the cylinder bore 34 .
- Intake and exhaust valves 40 and 41 can be provided for selectively opening and closing the intake and exhaust ports 38 and 39 , respectively.
- the intake and exhaust valves 40 and 41 can be selectively opened and closed in response to a certain crank angle ( ⁇ ) by a valve device (not shown) operatively connected to the crankshaft 22 .
- ⁇ crank angle
- other types of valve devices or drives can also be used, including variable valve timing systems.
- the intake device 17 can include intake pipes 44 extending from the respective cylinders 27 , and throttle valves 45 can be attached to the extended ends of the intake pipes 44 .
- throttle valves 45 can be attached to the extended ends of the intake pipes 44 .
- other types of systems can be sued with more or fewer throttle valves, including systems with no throttle valve at all.
- Such a system can use variable valve timing to meter induction air into the engine 11 .
- Each intake pipe 44 can have an intake passage 46 defined therein which communicates the ambient atmosphere to the intake port 38 through the throttle valve 45 .
- the throttle valve 45 is configured to adjust the opening of the intake passage 46 at the extended end of the intake pipe 44 , and thus “meter” an amount of air flowing therethrough.
- the exhaust device 19 can include an exhaust manifold 47 extending from the cylinders 27 .
- the exhaust manifold 47 can have an exhaust passage 48 defined therein which communicates the exhaust ports 39 to the ambient atmosphere.
- the exhaust manifold 47 can also include first to eighth upstream exhaust pipes 49 A to 49 H, first to fourth midway exhaust pipes 50 A to 50 D and a downstream exhaust pipe 51 .
- the first to eighth upstream exhaust pipes 49 A to 49 H can extend individually from the first to eighth cylinders 27 A to 27 H, respectively.
- the first to fourth midway exhaust pipes 50 A to 50 D can extend respectively from a joined portion of the extended ends of the first and fifth upstream exhaust pipes 49 A and 49 E, a joined portion of the extended ends of the second and sixth upstream exhaust pipes 49 B and 49 F, a joined portion of the extended ends of the third and seventh upstream exhaust pipes 49 C and 49 G, and a joined portion of the extended ends of the fourth and eighth upstream exhaust pipes 49 D and 49 H.
- the exhaust manifold 47 can further include first and second downstream exhaust pipes 51 A and 51 B.
- the first and second downstream exhaust pipes 51 A and 51 B can extend respectively from a joined portion of the extended ends of the first and third midway exhaust pipes 50 A and 50 C and a joined portion of the extended ends of the second and fourth midway exhaust pipes 50 B and 50 D, and can connect the respective joined portions to the ambient atmosphere.
- “to the ambient atmosphere” described above refers to both directly to the ambient atmospheric air and indirectly to the ambient atmosphere through the water 2 .
- Each pair of the first and fifth upstream exhaust pipes 49 A and 49 E, the second and sixth upstream exhaust pipes 49 B and 49 F, the third and seventh upstream exhaust pipes 49 C and 49 G, and the fourth and eighth upstream exhaust pipes 49 D and 49 H have approximately the same equivalent length.
- the first and fourth midway exhaust pipes 50 A to 50 D have approximately the same equivalent length.
- the second and third midway exhaust pipes 50 B and 50 C have approximately the same equivalent length.
- the first and fourth midway exhaust pipes 50 A and 50 D and the second and third midway exhaust pipes 50 B and 50 C can have a different equivalent length.
- Each exhaust port 39 and valve 41 combination can be configured to function as a de Laval nozzle.
- the exhaust port 39 can have an increasing cross sectional area as it extends to the downstream direction.
- exhaust 18 flowing from the cylinder bore 34 to the exhaust port 39 can be accelerated to Mach 1 by the constriction created between the valve 41 and its seat, then further accelerated beyond Mach 1 by the diverging shape of the port 39 to thereby cause a shock wave.
- each upstream exhaust pipe 49 can include a diffuser structure.
- the exhaust passage 48 can have an increasing cross sectional area as it extends toward the downstream side.
- the length of the upstream exhaust pipe 49 and the midway exhaust pipe 50 can be set to be sufficiently long such that the distance from the end face of the exhaust valve 41 on the cylinder bore 34 side to the downstream end of the midway exhaust pipe 50 can be about 300 mm or larger.
- other configurations and sizes can also be used.
- the upstream exhaust pipe 49 can have a diffuser structure, and in addition, the upstream exhaust pipe 49 and the midway exhaust pipe 50 can be relatively long.
- the shock wave generated in the exhaust port 39 , and a portion passed over the exhaust port 39 can form a dilatational wave more efficiently. That is, the negative pressure of exhaust pulses in the exhaust port 39 , the upstream exhaust pipe 49 and the midway exhaust pipe 50 can be increased.
- the downstream exhaust pipes 51 A, 51 B can have first and second expansion chamber cases 56 A and 56 B, respectively, forming the upstream sides thereof and connected to the downstream ends of the midway exhaust pipes 50 .
- the first and second expansion chamber cases 56 A and 56 B can serve as surge tanks.
- the downstream sides of the downstream exhaust pipes 51 A, 51 B can be formed by the above case 9 .
- the case 9 can include a pair of left and right first and second exhaust passages 48 A and 48 B for communicating the exhaust passages 48 in the first and second expansion chamber cases 56 A and 56 B individually to the water 2 .
- the first and second exhaust passages 48 A and 48 B form the downstream side of the exhaust passage 48 of the exhaust manifold 47 .
- the downstream ends of the first and second exhaust passages 48 A and 48 B in the case 9 can be each bifurcated into two passages.
- the (lower) bifurcated passages can have downstream end openings 48 a and 48 b communicating with the water 2 in a central area of rotation of the propeller 10 .
- the other (upper) bifurcated passages can have downstream end openings 48 c, 48 d formed in a longitudinal (vertical) midway part of the case 9 below the surface 2 a of the water 2 , above the central area of the propeller 10 and communicating with the water 2 .
- the downstream end openings 48 a to 48 d can be open rearward in the rear end face of the case 9 .
- a partition 52 can be provided for separating the upper downstream end openings 48 c, 48 d, from the lower downstream end openings 48 a and 48 b and the propeller 10 .
- the partition 52 can extend in the longitudinal (forward and backward) direction of the hull 3 .
- the partition 52 can also be formed together with left and right outer surfaces of the case 9 and can be supported by the case 9 .
- the partition 52 can have the shape of a strip extending longer in the longitudinal direction of the hull 3 .
- the partition 52 can also include a pair of left and right partition plates 52 a and a pair of left and right lugs 52 b.
- the left and right partition plates 52 a can project generally horizontally toward the lateral outside directions respectively from the left and right outer surfaces of the case 9 to be integral therewith.
- the left and right lugs 52 b can project upwardly from the respective laterally outwardly projected ends of the partition plates 52 a to be integral therewith.
- a water guide 53 can be provided for guiding the water 2 in the rearward direction in cooperation with the partition 52 , when the watercraft 1 is driven forwardly.
- the water guide 53 can be positioned below the surface 2 a of the water 2 and above and in proximity to the upper downstream end openings 48 c, 48 d of the first and second exhaust passages 48 A and 48 B.
- the water guide 53 can face toward the partition 52 in a vertical direction.
- the water guide 53 can extend generally parallel to the partition 52 , and can be formed together with the left and right outer surfaces of the case 9 to be supported by the case 9 .
- a pair of left and right water passages 54 can be defined between the partition 52 and the water guide 53 to extend generally straight in the longitudinal direction of the hull 3 .
- the expansion chamber case 56 has a cross sectional area twice as large as or larger than twice the total cross sectional area of the downstream ends of the midway exhaust pipes 50 . This provides effective damping on vibration caused by the pressure of the pulses of exhaust 18 flowing from the midway exhaust pipes 50 into the expansion chamber case 56 , so that mutual interference of the exhausts 18 can be reduced and/or prevented.
- the inner bottom 56 a of the expansion chamber case 56 can be inclined downwardly toward the upstream end of the exhaust passage 48 formed in the case 9 .
- the water 2 that may collect in a bottom part in the expansion chamber case 56 will flow through the exhaust passage 48 in the case 9 to be drained.
- An idling exhaust passage 57 can be formed in the case 9 ( FIGS. 2 and 3 ) for communicating longitudinal midway parts of the exhaust passage 48 in the downstream exhaust pipes 51 and the midway exhaust pipes 50 to the ambient atmosphere above the surface of the water 2 .
- the upstream exhaust pipes 49 , the midway exhaust pipes 50 and the expansion chamber cases 56 of the downstream exhaust pipes 51 of the exhaust manifold 47 , and the case 9 can have individual water jackets 58 . Cooling water can be pumped through the water jackets 58 . As such, the water jackets 58 can prevent the temperature of the exhaust manifold 47 from increasing due to the exhaust 18 .
- each cylinder 27 can be provided with a first air passage 65 and a reed valve 66 so that first secondary air 63 can be supplied to the upstream side of the exhaust port 39 .
- second air passages 67 and reed valves can be provided so that second secondary air 64 can be supplied to the exhaust passage 48 in the midway exhaust pipes 50 .
- First O 2 sensors 72 and second O 2 sensors 73 can be provided.
- the first O 2 sensor 72 can be disposed downstream of the first and second secondary airs 63 , 64 , and can be configured to detect the components (concentration of oxygen) of the exhaust 18 flowing through the midway exhaust pipe 50 .
- the second O 2 sensor 73 can be also disposed downstream of the first and second secondary airs 63 , 64 , and can be configured to detect the components of the exhaust 18 flowing through the downstream end of the expansion chamber case 56 .
- a cover 74 can be provided for covering the second O 2 sensor 73 from above. As a result, water droplets can be prevented from falling onto the O 2 sensor 73 . Accordingly, the O 2 sensor can be prevented from being damaged due to water droplets.
- the opening of the intake passage 46 adjusted by the throttle valve 45 , the fuel supply amount, and the supply amount of secondary airs 63 , 64 can be controlled automatically. Due to such control, enhanced purification of the exhaust 18 can be provided.
- the crankshaft 22 makes rotation (R), and the first to eighth cylinders 27 A to 27 H can be ignited sequentially in that order.
- the ignitions can be performed at predetermined intervals of crank angle ( ⁇ ), preferably at a 90°. It is understood, however, that the ignitions may not be performed at predetermined intervals but a plurality of (two) cylinders may be ignited almost simultaneously.
- Exhaust flows 18 are discharged sequentially from the cylinders 27 through the exhaust manifold 47 in the same order as the cylinders 27 are ignited.
- the pressure of the exhaust 18 can be relatively high and the amount of the exhaust 18 can be relatively large.
- most of the exhaust 18 can be discharged into the water 2 against water pressure through the exhaust passage 48 of the exhaust manifold 47 .
- a small amount of the rest of the exhaust 18 can be discharged to the ambient atmosphere through the idling exhaust passage 57 .
- the rotation (R) of the crankshaft 22 by the operation of the engine drives the propeller 10 via the power transmission apparatus 12 to thereby propel the watercraft 1 .
- the pressure of the exhaust 18 can be relatively low and the amount of the exhaust can be relatively small.
- the exhaust 18 can be prevented from being discharged into the water 2 through the exhaust passage 48 of the exhaust manifold 47 , and thus most of the exhaust 18 can be discharged to the ambient atmosphere through the idling exhaust passage 57 .
- regulating parts 78 can be formed at the downstream ends of the respective midway exhaust pipes 50 , or midway parts of the exhaust passage 48 thereof
- the opening of the regulating parts 78 can be made variable by a plurality of (four) butterfly regulating valves 79 individually provided at the downstream ends of the midway exhaust pipes 50 .
- the regulating valves 79 can be operatively connected to each other to selectively open and close together.
- An actuator (not shown) can be provided for moving the regulating valves. It is understood that the regulating valves 79 may be moved individually.
- the exhaust manifold 47 includes the first to eighth upstream exhaust pipes 49 A to 49 H extending respectively from the first to eighth cylinders 27 A to 27 H.
- the first to fourth midway exhaust pipes 50 A to 50 D extend respectively from a joined portion of the extended ends of the first and fifth upstream exhaust pipes 49 A and 49 E, a joined portion of the extended ends of the second and sixth upstream exhaust pipes 49 B and 49 F, a joined portion of the extended ends of the third and seventh upstream exhaust pipes 49 C and 49 G, and a joined portion of the extended ends of the fourth and eighth upstream exhaust pipes 49 D and 49 H.
- the first and second downstream exhaust pipes 51 A and 51 B extend respectively from a joined portion of the extended ends of the first and third midway exhaust pipes 50 A and 50 C and a joined portion of the extended ends of the second and fourth midway exhaust pipes 50 B and 50 D for connecting the respective joined portion to the ambient atmosphere.
- an exhaust 18 from the first cylinder 27 A flows sequentially through the first upstream exhaust pipe 49 A, the first midway exhaust pipe 50 A and the first downstream exhaust pipe 51 A to the ambient atmosphere.
- an exhaust 18 from the second cylinder 27 B flows sequentially through the second upstream exhaust pipe 49 B, the second midway exhaust pipe 50 B and the second downstream exhaust pipe 51 B to the ambient atmosphere.
- an exhaust 18 can be discharged from the third cylinder 27 C. This exhaust 18 will be discussed in greater detail below.
- an exhaust 18 from the fourth cylinder 27 D flows sequentially through the fourth upstream exhaust pipe 49 D, the fourth midway exhaust pipe 50 D and the second downstream exhaust pipe 51 B to the ambient atmosphere.
- the subsequent pulses of exhaust 18 discharged from the second cylinder 27 B and the fourth cylinder 27 D can be prevented from interfering with the exhaust 18 from the first cylinder 27 A in the upstream exhaust pipes 49 , the midway exhaust pipes 50 and the downstream exhaust pipes 51 .
- the exhaust 18 from the third cylinder 27 C described above flows sequentially through the third upstream exhaust pipe 49 C, the third midway exhaust pipe 50 C and the first downstream exhaust pipe 51 A to the ambient atmosphere.
- both the exhaust 18 from the first cylinder 27 A and the exhaust 18 from the third cylinder 27 C flow through the first downstream exhaust pipe 51 A.
- the exhaust 18 from the third cylinder 27 C may interfere with the exhaust 18 from the first cylinder 27 A in the first downstream exhaust pipe 51 A.
- the first upstream exhaust pipe 49 A and the first midway exhaust pipe 50 A, through which the exhaust 18 from the first cylinder 27 A flows, and the third upstream exhaust pipe 49 C and the third midway exhaust pipe 50 C, through which the exhaust 18 from the third cylinder 27 C flows, can be separate from each other and have a relatively long length.
- the first and third cylinders 27 A and 27 C can be far away from each other because of the first exhaust passage 48 .
- the exhaust 18 from the third cylinder 27 C can be prevented from interfering with the exhaust 18 from the first cylinder 27 A in the first downstream exhaust pipe 51 A.
- the first cylinder 27 A and the fifth cylinder 27 E can be positioned in proximity to each other because the first and fifth upstream exhaust pipes 49 A and 49 E, extending from the first cylinder 27 A and the fifth cylinder 27 E, can be joined to each other.
- the ignition interval between the first cylinder 27 A and the fifth cylinder 27 E can be significantly long due to ignitions of the second to fourth cylinders 27 B to 27 D occurring therebetween.
- overlapping of the exhaust strokes of the first cylinder 27 A and the fifth cylinder 27 E can be prevented.
- the exhaust 18 from the fifth cylinder 27 E can be prevented from interfering with the exhaust 18 from the first cylinder 27 A in the first and fifth upstream exhaust pipes 49 A and 49 E.
- the interval between ignition of the first cylinder 27 A and ignitions of the sixth to eighth cylinders 27 F to 27 H can be even longer.
- the exhausts 18 from the sixth to eighth cylinders 27 F to 27 H can be prevented from interfering with the exhaust 18 from the first cylinder 27 A.
- the above description of the exhaust 18 from the first cylinder 27 A can apply to the exhaust 18 from the other cylinders 27 .
- interference of the exhaust pulses in the engine 11 can be prevented, and thus desired exhaust pulses having a sufficiently high negative pressure can be obtained. Therefore, the enhanced performance of the engine 11 can be achieved more reliably.
- each pair of the first and fifth upstream exhaust pipes 49 A and 49 E, the second and sixth upstream exhaust pipes 49 B and 49 F, the third and seventh upstream exhaust pipes 49 C and 49 G, and the fourth and eighth upstream exhaust pipes 49 D and 49 H have approximately the same equivalent length.
- the exhausts 18 from the first to eighth cylinders 27 A to 27 H can be more likely to interfere with each other: the exhausts 18 from the first and fifth cylinders 27 A and 27 E in the first and fifth upstream exhaust pipes 49 A and 49 E joined to each other; the exhausts 18 from the second and sixth cylinders 27 B and 27 F in the second and sixth upstream exhaust pipes 49 B and 49 F; the exhausts 18 from the third and seventh cylinders 27 C and 27 G in the third and seventh upstream exhaust pipes 49 C and 49 G; and the exhausts 18 from the fourth and eighth cylinders 27 D and 27 H in the fourth and eighth upstream exhaust pipes 49 D and 49 H.
- the first and fifth upstream exhaust pipes 49 A and 49 E for example, in which interference of exhaust can be more likely to occur, have approximately the same equivalent length.
- interference of exhaust 18 from the first cylinder 27 A with an exhaust 18 from the fifth cylinder 27 E ignited fourth after the first cylinder 27 A and interference of the exhaust 18 from the fifth cylinder 27 E with an exhaust 18 from the first cylinder 27 A ignited fourth after the fifth cylinder 27 E can be set to about the same level. That is, interference between the exhausts 18 from the first and fifth cylinders 27 A and 27 E for example can be minimized and more balanced. This ensures the excellent and stable performance of the engine.
- the engine 11 having the plurality of cylinders 27 , the first expansion chamber case 56 A for collecting therein exhausts 18 from the first part of the cylinders 27 , and the second expansion chamber case 56 B for collecting therein exhausts 18 from the second part of the cylinders 27 can be provided.
- the first and second exhaust passages 48 A and 48 B can be formed extending individually from the first and second expansion chamber cases 56 A and 56 B, respectively, and communicating with the water 2 at the downstream end openings 48 a to 48 d.
- the cylinders 27 A, 27 C, 27 E, 27 G ignited in odd-numbered order can be referred to as the first part of the cylinders 27
- the cylinders 27 B, 27 D, 27 F, 27 H ignited in even-numbered order can be referred to as the second part of the cylinders 27 .
- the exhaust 18 from the cylinders ignited in odd-numbered (or even-numbered) order can be most significantly interfered with the subsequent exhausts 18 from the cylinders ignited in even-numbered (or odd-numbered) order.
- the pulses of exhaust 18 from the cylinders 27 ignited in odd-numbered order and the pulses of exhaust 18 from the cylinders 27 ignited in even-numbered order can be discharged individually into the water 2 .
- the pulses of exhaust 18 from the cylinders 27 ignited in odd-numbered order and the pulses of exhaust 18 from the cylinders 27 ignited in even-numbered order can be discharged individually into the water 2 .
- the downstream end openings 48 c, 48 d of the first and second exhaust passages 48 A and 48 B can be formed in the longitudinal midway part of the case 9 below the surface 2 a of the water 2 .
- the partition 52 can be provided extending in the longitudinal direction of the hull 3 to separate the propeller 10 and the downstream end openings 48 c, 48 d and being supported by the case 9 .
- the water guide 53 can be positioned above the downstream end openings 48 c, 48 d of the first and second exhaust passages 48 A and 48 B, facing the partition 52 in a vertical direction, extending generally parallel to the partition 52 and can be supported by the case 9 .
- the exhausts 18 from the cylinders 27 are discharged into the water 2 through the downstream end openings 48 c, 48 d.
- the exhaust 18 can be carried farther away from the watercraft 1 in the rearward direction by the water flowing rearwardly along the water passages 54 between the partition 52 and the water guide 53 . Then, the exhausts 18 come up from the water 2 to be released into the ambient atmosphere.
- the downstream end openings 48 c, 48 d described above can be positioned nearer to the surface 2 a of the water 2 as compared to the case where the downstream end openings 48 c, 48 d are formed at the lower end of the case 9 .
- the exhausts 18 discharged into the water 2 through the downstream end openings 48 c, 48 d can be prevented from being released immediately into the ambient atmosphere. Therefore, the influence of the exhaust noise on the passengers on the watercraft 1 can be reduced advantageously.
- the engine 11 may be a four-cylinder or six-cylinder engine. It is also understood that the banks 24 , 25 can be arranged in a laterally inverse form. It is also understood that the lower and upper downstream end openings 48 a to 48 d in the case 9 can be only the lower or upper downstream end openings.
- FIGS. 11 to 21 illustrate modifications of the exhaust systems and engines described above with reference to FIGS. 1-10 .
- the modifications described below can have many parts, components, and methods of use in common with the exhaust systems and engines of FIGS. 1-10 . Therefore, those parts and components are identified with the same reference numerals in the drawings and their description, as well as a description of a method if use, is not repeated. Their optional differences, however, are described below.
- the configurations of the parts and components described above can be combined with the modifications described below in various ways.
- one (left) bank 24 of the banks 24 , 25 can be formed by the first, third, seventh and fifth cylinders 27 A, 27 C, 27 G and 27 E.
- the other (right) bank 25 can be formed by the second, fourth, eighth and sixth cylinders 27 B, 27 D, 27 H and 27 F.
- the first, third, seventh and fifth upstream exhaust pipes 49 A, 49 C, 49 G and 49 E, the first and third midway exhaust pipes 50 A and 50 C, and the first downstream exhaust pipe 51 A, which can be associated with the first, third, seventh and fifth cylinders 27 A, 27 C, 27 G and 27 E, can be arranged to the left of the crankshaft 22 .
- the other exhaust pipes associated with the second, fourth, eighth and sixth cylinders 27 B, 27 D, 27 H and 27 F can be arranged to the right of the crankshaft 22 .
- each midway exhaust pipe 50 can have a plurality of (two) catalysts 60 , 61 disposed therein longitudinally.
- the catalysts 60 , 61 can be three-way catalysts for purifying exhaust 18 .
- the catalysts 60 , 61 can also have a longitudinal length longer than a radial length in the exhaust passage 48 .
- the second secondary air 64 supplied to the downstream side of the first exhaust passage 48 can be supplied to a part of the first exhaust passage 48 between the catalysts 60 , 61 via the second air passage 67 and the reed valve 68 .
- Both the O 2 sensors 72 , 73 can be disposed downstream of the catalysts 60 , 61 .
- the catalysts 60 , 61 for purifying exhaust can be disposed in the exhaust passage 48 in the exhaust manifold 47 .
- the first air passage 65 can be formed for supplying first secondary air 63 to the upstream side of the catalysts 60 , 61 in the exhaust passage 48 .
- first and second secondary airs 63 and 64 can be sucked more smoothly into the exhaust passage 48 due to the negative pressure. That is, a larger amount of first and second secondary airs 63 , 64 can be supplied into the exhaust passage 48 .
- the air-fuel ratio (A/F) of the mixture to be supplied to the engine body 15 of the engine 11 by the intake device 17 is small (rich)
- the exhaust air-fuel ratio on the upstream side of the catalysts 60 , 61 can be set to a desired value such as a theoretical air-fuel ratio. More reliable purification of exhaust 18 can be thereby achieved. That is, as a result of such purification of exhaust 18 , the enhanced performance of the engine 11 can be achieved more reliably.
- the catalysts 60 , 61 have a longitudinal length longer than a radial length in the exhaust passage 48 .
- the above engine 11 can be incorporated in the outboard motor 4 .
- the engine 11 incorporated into an outboard motor will often be operated at a maximum output point under full load.
- the flow speed of exhaust 18 in the exhaust passage 48 becomes relatively high.
- the catalysts 60 , 61 can have a longer length as described above. This ensures that the exhaust 18 is exposed to the catalysts 60 , 61 for a longer amount of time. As a result, more reliable purification of the exhaust 18 can be achieved. That is, the enhanced performance of the engine 11 can be achieved more reliably.
- midway exhaust passages 50 may be shorter in length as indicated by chain double-dashed lines in FIG. 11 .
- the engine and exhaust systems therein can be essentially the same as that of FIGS. 11-14 except that generally the entire exhaust device 19 is arranged in front of the engine body 15 . Additionally, balancers 82 can be operatively connected to the crankshaft 22 .
- the idling exhaust passage 57 can be formed for communicating longitudinal “midway parts” of the exhaust passage 48 in the midway exhaust pipes 50 to the ambient atmosphere above the surface of the water 2 .
- the regulating part 78 having the regulating valve 79 to vary its opening can be provided on the downstream side of and in proximity to the “midway part” of the exhaust passage 48 .
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Abstract
Description
- This application is based on and claims priority to Japanese Patent Application No. 2006-204700, filed Jul. 27, 2006, the entire contents of which is hereby expressly incorporated by reference.
- 1. Field of the Inventions
- The present inventions relate to exhaust devices, for example, exhaust devices that can be used for outboard motors which can reduce or prevent mutual interference of exhaust pulses from a plurality of cylinders of an engine.
- 2. Description of the Related Art
- Japanese Patent Document JP-A-2000-265836 discloses a known exhaust device of a multicylinder engine. In this engine, one set of exhaust passages extending respectively from a plurality of cylinders subjected to odd-numbered ignitions are joined at a point to form a first joined passage and another set of exhaust passages extending respectively from a plurality of cylinders subjected to even-numbered ignitions are joined at another point to form a second joined passage. These joined passages are further joined at another point into single consolidated exhaust passage. The downstream end of the consolidated exhaust passage communicates with the ambient atmosphere. With this structure, exhaust pulses from the cylinders ignited in serial order are prevented from interfering with each other, and thus enhanced performance of the engine is provided.
- The engine described in Japanese Patent Document JP-A-2000-265836 is used as a drive source for an outboard motor. It is generally desirable to make the engines of outboard motors as small as possible to reduce the aerodynamic drag created by the outboard motor, as well as for other reasons. To make such engines more compact, the length of the exhaust passages can be shortened. In this case, the cylinders subjected to odd-numbered explosions, which occur prior, and the cylinders subjected to even-numbered explosions, which occur later and subsequently to the former, will be positioned in proximity to each other because of the length of the shortened exhaust passages described above.
- As a result, exhausts from the cylinders subjected to later explosions tend to interfere with exhausts from the cylinders subjected to prior explosions. Thus, in the exhaust passages extending from the cylinders subjected to earlier explosions, desired exhaust pulses having a sufficiently high negative pressure may not be obtained.
- When the negative pressure of exhaust pulses is not sufficiently high as described above, the exhaust is not released properly from the cylinders. This causes a knocking due to the burnt gas left in the cylinders, a misfiring, increased pumping losses, and decreased volumetric efficiency due to an improper intake of fresh air. As a result, engine output, fuel economy and exhaust efficiency may decrease.
- Thus, in accordance with an embodiment, an exhaust device for an outboard motor can comprise an engine having a plurality of cylinders. A first expansion chamber case can be configured to collect therein exhaust from a first part of the plurality of cylinders. A second expansion chamber case can be configured to collect therein exhaust from a second part of the plurality of cylinders. First and second exhaust passages can extend individually from the first and second expansion chamber cases, respectively, each of the first and second exhaust passages can have a downstream end opening communicating with water.
- In accordance with another embodiment, an outboard motor can comprise an engine having a plurality of cylinders. A case can include a lower portion configured to be submerged in water during operation of the outboard motor. A first expansion chamber case can be configured to collect therein exhaust from a first group of the plurality of cylinders. A second expansion chamber case can be configured to collect therein exhaust from a second group of the plurality of cylinders. First and second exhaust passages can extend individually from the first and second expansion chamber cases, respectively, each of the first and second exhaust passages having separate downstream end openings disposed on the lower portion.
- The above-mentioned and other features of the inventions disclosed herein are described below with reference to the drawings of the preferred embodiments. The illustrated embodiments are intended to illustrate, but not to limit the inventions. The drawings contain the following Figures.
-
FIG. 1 is a schematic diagram generally illustrating an engine in accordance with an embodiment. -
FIG. 2 is a schematic side view of a rear part of a watercraft including an outboard motor which, in turn, can include the engine ofFIG. 1 . -
FIG. 3 is a partial rear elevational view of a lower portion of the outboard motor. -
FIG. 4 is a cross-sectional view taken along the line IV-IV inFIG. 3 . -
FIG. 5 is a schematic side elevational view of the engine, with certain components of the exhaust system shown in phantom line. -
FIG. 6 is a rear elevational view of the engine with certain components of the exhaust system shown in phantom line. -
FIG. 7 is a partial bottom plan and schematic cross-sectional view of the engine. -
FIG. 8 is an enlarged detailed cross-sectional view of an exhaust port of the engine. -
FIG. 9 is a perspective view of a portion of an exhaust device. -
FIG. 10 is a plan and cross-sectional view of regulating parts and regulating valves that can be used with the exhaust device. -
FIG. 11 is a schematic side elevational view of a modification of the engine ofFIGS. 1-10 , with certain components of the exhaust system shown in phantom line. -
FIG. 12 is a front view of the engine ofFIG. 11 , with certain covers removed and certain components shown in phantom line. -
FIG. 13 is a top plan and partial cross-sectional view of the engine ofFIG. 11 . -
FIG. 14 is an enlarged cross-sectional view of a portion ofFIG. 11 . -
FIG. 15 is a schematic side elevational view of another modification of the engine ofFIGS. 1-10 , with certain components of the exhaust system shown in phantom line. -
FIG. 16 is a front view of the engine ofFIG. 15 . -
FIG. 17 is a plan view of a portion of the engine ofFIG. 15 . -
FIG. 18 is a partial bottom plan and schematic cross-sectional view of the engine ofFIG. 15 . -
FIG. 19 is a perspective view of a portion of the exhaust device that can be used with the exhaust system of the engine ofFIG. 15 . -
FIG. 20 is an enlarged cross-sectional view of a portion ofFIG. 17 . -
FIG. 21 is an enlarged cross-sectional view of another portion ofFIG. 17 . - Improved exhaust systems for an engine 11 (
FIG. 1 ) are disclosed herein. Although the present exhaust systems are illustrated and described in the context of an outboard motor, certain aspects of the present inventions can be used with engines of other types of vehicles, as well as with other types of prime movers. - In some embodiments, an exhaust device for an outboard motor is configured to reduce or prevent mutual interference of exhausts from a plurality of cylinders of an engine of the outboard motor, thereby providing enhanced performance of the engine more reliably.
- For example, in some embodiments, an exhaust device for an outboard motor can include an engine having a plurality of cylinders. A first expansion chamber case can be configured to collect therein exhaust from a first part of the plurality of cylinders. A second expansion chamber case can also be configured to collect therein exhaust from a second part of the plurality of cylinders. First and second exhaust passages can extend individually from the first and second expansion chamber cases, respectively, and communicate with water at the downstream end openings.
- Referring to FIGS. 1 to 4, a small watercraft 1 (
FIG. 2 ) can be designed to float on the surface ofwater 2 such as the sea. The arrow Fr indicates the forward direction in which thewatercraft 1 is driven. The term “left and right” used herein refers to the width direction of thewatercraft 1 with respect to the above forward direction. - The
watercraft 1 can include ahull 3 designed to float on the surface of thewater 2, and anoutboard motor 4 supported at the stern of thehull 3. Theoutboard motor 4 can include anoutboard motor body 5 for producing propulsive force to selectively drive thehull 3 forward or rearward, and abracket 6 for supporting theoutboard motor body 5 on thehull 3. - The
outboard motor body 5 can include acase 9, apropeller 10, anengine 11, apower transmission apparatus 12 and acowling 13. Thecase 9 can extend generally vertically, and can be supported on thehull 3 by thebracket 6. - A lower portion of the
case 9 can be designed to be submerged in thewater 2. Thepropeller 10 is supported at the lower end of thecase 9. Theengine 11 is supported at the upper end of thecase 9. Thepower transmission apparatus 12 is enclosed in thecase 9, and operatively connects thepropeller 10 to theengine 11. Thecowling 13 selectively covers and uncovers theengine 11 on the outside thereof It should be noted that the “surface 2a of thewater 2” described above is the water level during thewatercraft 1 being driven forward, and can fluctuate vertically to some degree. - The
power transmission apparatus 12 can include agear switching device 14 for changing the driving state of thepropeller 10 between a forward drive mode, a reverse drive mode and a neutral mode, through a user's manual operation. The operation of theswitching device 14 allows thehull 3 to be selectively driven either forward or rearward, or to be allowed to drift, during operation of theengine 11. - Referring to FIGS. 1 to 8, the
engine 11 is a four-stroke V-type engine having a plurality of (eight) cylinders, and is used as a drive source for theoutboard motor 4. However, this is merely one type of engine that can be used. Those skilled in the art readily appreciate that the present exhaust systems and exhaust components can be used with any of a variety of engines having other numbers of cylinders, and/or other cylinder arrangements, and/or operating on other principles of operation (diesel, 2-stroke, rotary, etc.). - The
engine 11 includes anengine body 15, anintake device 17 and anexhaust device 19. Theengine body 15 is supported on the top of thecase 9. Theintake device 17 supplies a mixture ofambient air 16 and fuel to theengine body 15. Theexhaust device 19 discharges burnt gas resulting from combustion of the mixture in theengine body 15 to the outside of theengine 11 asexhaust 18. Thecase 9 has anoil tank 20 having stored therein lubricant for lubricating various parts of theengine body 15. - The
engine 11 can include anengine body 15, anintake device 17 and anexhaust device 19. Thecrankcase 23 can be supported on the top of thecase 9, and can support acrankshaft 22 for rotation about avertical axis 21. - The left and
right banks crankcase 23 in a V-configuration as viewed in the bottom view of the engine 11 (FIG. 7 ). The angle made by thebanks eighth cylinders 27A to 27H, is approximately 60°. The first toeighth cylinders 27A to 27H are ignited sequentially in that order. - For example, one (left)
bank 24 of thebanks seventh cylinders cylinders - The other (right)
bank 25 can be formed by the eighth, third, fifth andsecond cylinders cylinders eighth cylinders 27A to 27H can be arranged in the downward direction in order of thefirst cylinder 27A, theeighth cylinder 27H, thefourth cylinder 27D, thethird cylinder 27C, thesixth cylinder 27F, thefifth cylinder 27E, theseventh cylinder 27G and thesecond cylinder 27B. - With reference to
FIG. 7 , thecrankshaft 22 can include a crankmain shaft 30, crankarms 31 andcrankpins 32. The crankmain shaft 30 can be positioned about theaxis 21, and can have journals supported by thecrankcase 23. - The crank
arms 31 can project from the crankmain shaft 30. Thecrankpins 32 can be supported by the respective crankarms 31, and associated respectively with the first toeighth cylinders 27A to 27H. The angle made by thebanks crankpins 32 associated with the first toeighth cylinders 27A to 27H can be arranged in the following manner, as viewed in the bottom view of the engine 11 (FIG. 7 ). - For example, the
crankpins 32 associated with the first, eighth, fourth, third, seventh, second, sixth and fifth cylinders can be arranged in that order in the counterclockwise direction of thecrankshaft 22. The angle made by thecrankpins 32 associated with each pair of the first and eighth cylinders, the fourth and third cylinders, the seventh and second cylinders, and the sixth and fifth cylinders can be 30°. The angle made by thecrankpins 32 associated with each pair of the eighth and fourth cylinders, the third and seventh cylinders, the second and sixth cylinders, and the fifth and first cylinders can be 60°. That is, thecrankshaft 22 can be of similar type to that of so-called cross plane/double plane/dual plane crank type of a V-type, multicylinder engine having a bank angle of 90°. - Each of first to
eighth cylinders 27A to 27H can include apiston 35 and a connectingrod 36. Thepiston 35 can be fitted in a cylinder bore 34 of each cylinder in a manner sliding axially therealong. The connectingrod 36 can operatively connect thepiston 35 and thecrankpin 32 of thecrankshaft 22. - Each
cylinder 27 can have intake andexhaust ports exhaust valves exhaust ports exhaust valves crankshaft 22. However, other types of valve devices or drives can also be used, including variable valve timing systems. - The
intake device 17 can includeintake pipes 44 extending from therespective cylinders 27, andthrottle valves 45 can be attached to the extended ends of theintake pipes 44. However, other types of systems can be sued with more or fewer throttle valves, including systems with no throttle valve at all. Such a system can use variable valve timing to meter induction air into theengine 11. - Each
intake pipe 44 can have anintake passage 46 defined therein which communicates the ambient atmosphere to theintake port 38 through thethrottle valve 45. Thethrottle valve 45 is configured to adjust the opening of theintake passage 46 at the extended end of theintake pipe 44, and thus “meter” an amount of air flowing therethrough. - Referring to FIGS. 1 to 8, the
exhaust device 19 can include anexhaust manifold 47 extending from thecylinders 27. Theexhaust manifold 47 can have anexhaust passage 48 defined therein which communicates theexhaust ports 39 to the ambient atmosphere. - The
exhaust manifold 47 can also include first to eighthupstream exhaust pipes 49A to 49H, first to fourthmidway exhaust pipes 50A to 50D and adownstream exhaust pipe 51. The first to eighthupstream exhaust pipes 49A to 49H can extend individually from the first toeighth cylinders 27A to 27H, respectively. - The first to fourth
midway exhaust pipes 50A to 50D can extend respectively from a joined portion of the extended ends of the first and fifthupstream exhaust pipes upstream exhaust pipes upstream exhaust pipes upstream exhaust pipes - The
exhaust manifold 47 can further include first and seconddownstream exhaust pipes downstream exhaust pipes midway exhaust pipes midway exhaust pipes water 2. - Each pair of the first and fifth
upstream exhaust pipes upstream exhaust pipes upstream exhaust pipes upstream exhaust pipes midway exhaust pipes 50A to 50D, the first and fourthmidway exhaust pipes midway exhaust pipes midway exhaust pipes midway exhaust pipes - Each
exhaust port 39 andvalve 41 combination can be configured to function as a de Laval nozzle. For example, theexhaust port 39 can have an increasing cross sectional area as it extends to the downstream direction. As a result, during the start of the valve opening motion of theexhaust valve 41,exhaust 18 flowing from the cylinder bore 34 to theexhaust port 39, can be accelerated toMach 1 by the constriction created between thevalve 41 and its seat, then further accelerated beyondMach 1 by the diverging shape of theport 39 to thereby cause a shock wave. - The
exhaust passage 48 of eachupstream exhaust pipe 49 can include a diffuser structure. For example, theexhaust passage 48 can have an increasing cross sectional area as it extends toward the downstream side. The length of theupstream exhaust pipe 49 and themidway exhaust pipe 50 can be set to be sufficiently long such that the distance from the end face of theexhaust valve 41 on the cylinder bore 34 side to the downstream end of themidway exhaust pipe 50 can be about 300 mm or larger. However, other configurations and sizes can also be used. - For example, the
upstream exhaust pipe 49 can have a diffuser structure, and in addition, theupstream exhaust pipe 49 and themidway exhaust pipe 50 can be relatively long. As a result, the shock wave generated in theexhaust port 39, and a portion passed over theexhaust port 39 can form a dilatational wave more efficiently. That is, the negative pressure of exhaust pulses in theexhaust port 39, theupstream exhaust pipe 49 and themidway exhaust pipe 50 can be increased. - The
downstream exhaust pipes expansion chamber cases midway exhaust pipes 50. The first and secondexpansion chamber cases - The downstream sides of the
downstream exhaust pipes above case 9. For example, thecase 9 can include a pair of left and right first andsecond exhaust passages exhaust passages 48 in the first and secondexpansion chamber cases water 2. The first andsecond exhaust passages exhaust passage 48 of theexhaust manifold 47. - The downstream ends of the first and
second exhaust passages case 9 can be each bifurcated into two passages. Of the bifurcated passages of the first andsecond exhaust passages downstream end openings water 2 in a central area of rotation of thepropeller 10. The other (upper) bifurcated passages can havedownstream end openings case 9 below thesurface 2 a of thewater 2, above the central area of thepropeller 10 and communicating with thewater 2. Thedownstream end openings 48 a to 48 d can be open rearward in the rear end face of thecase 9. - With continued reference to
FIGS. 2 and 3 , apartition 52 can be provided for separating the upperdownstream end openings downstream end openings propeller 10. In some embodiments, thepartition 52 can extend in the longitudinal (forward and backward) direction of thehull 3. - The
partition 52 can also be formed together with left and right outer surfaces of thecase 9 and can be supported by thecase 9. Thepartition 52 can have the shape of a strip extending longer in the longitudinal direction of thehull 3. - The
partition 52 can also include a pair of left andright partition plates 52 a and a pair of left andright lugs 52 b. The left andright partition plates 52 a can project generally horizontally toward the lateral outside directions respectively from the left and right outer surfaces of thecase 9 to be integral therewith. The left andright lugs 52 b can project upwardly from the respective laterally outwardly projected ends of thepartition plates 52 a to be integral therewith. - A
water guide 53 can be provided for guiding thewater 2 in the rearward direction in cooperation with thepartition 52, when thewatercraft 1 is driven forwardly. Thewater guide 53 can be positioned below thesurface 2 a of thewater 2 and above and in proximity to the upperdownstream end openings second exhaust passages - With continued reference to
FIGS. 2 and 3 , thewater guide 53 can face toward thepartition 52 in a vertical direction. Thewater guide 53 can extend generally parallel to thepartition 52, and can be formed together with the left and right outer surfaces of thecase 9 to be supported by thecase 9. A pair of left andright water passages 54 can be defined between thepartition 52 and thewater guide 53 to extend generally straight in the longitudinal direction of thehull 3. - As seen axially along the downstream ends of the midway exhaust pipes 50 (
FIG. 7 ), in the vicinity of the downstream ends of themidway exhaust pipes 50, theexpansion chamber case 56 has a cross sectional area twice as large as or larger than twice the total cross sectional area of the downstream ends of themidway exhaust pipes 50. This provides effective damping on vibration caused by the pressure of the pulses ofexhaust 18 flowing from themidway exhaust pipes 50 into theexpansion chamber case 56, so that mutual interference of theexhausts 18 can be reduced and/or prevented. - With reference to
FIG. 6 , the inner bottom 56 a of theexpansion chamber case 56 can be inclined downwardly toward the upstream end of theexhaust passage 48 formed in thecase 9. As a result, thewater 2 that may collect in a bottom part in theexpansion chamber case 56 will flow through theexhaust passage 48 in thecase 9 to be drained. - An idling
exhaust passage 57 can be formed in the case 9 (FIGS. 2 and 3 ) for communicating longitudinal midway parts of theexhaust passage 48 in thedownstream exhaust pipes 51 and themidway exhaust pipes 50 to the ambient atmosphere above the surface of thewater 2. - The
upstream exhaust pipes 49, themidway exhaust pipes 50 and theexpansion chamber cases 56 of thedownstream exhaust pipes 51 of theexhaust manifold 47, and thecase 9 can haveindividual water jackets 58. Cooling water can be pumped through thewater jackets 58. As such, thewater jackets 58 can prevent the temperature of theexhaust manifold 47 from increasing due to theexhaust 18. - Referring to
FIGS. 1 and 8 , eachcylinder 27 can be provided with afirst air passage 65 and areed valve 66 so that firstsecondary air 63 can be supplied to the upstream side of theexhaust port 39. Referring toFIGS. 1 and 6 ,second air passages 67 and reed valves can be provided so that secondsecondary air 64 can be supplied to theexhaust passage 48 in themidway exhaust pipes 50. - First O2 sensors 72 and second O2 sensors 73 can be provided. The first O2 sensor 72 can be disposed downstream of the first and second secondary airs 63, 64, and can be configured to detect the components (concentration of oxygen) of the
exhaust 18 flowing through themidway exhaust pipe 50. The second O2 sensor 73 can be also disposed downstream of the first and second secondary airs 63, 64, and can be configured to detect the components of theexhaust 18 flowing through the downstream end of theexpansion chamber case 56. - A
cover 74 can be provided for covering the second O2 sensor 73 from above. As a result, water droplets can be prevented from falling onto the O2 sensor 73. Accordingly, the O2 sensor can be prevented from being damaged due to water droplets. - Based on the detection signals from the O2 sensors 72, 73, the opening of the
intake passage 46 adjusted by thethrottle valve 45, the fuel supply amount, and the supply amount ofsecondary airs exhaust 18 can be provided. - When the
engine 11 is driven, thecrankshaft 22 makes rotation (R), and the first toeighth cylinders 27A to 27H can be ignited sequentially in that order. The ignitions can be performed at predetermined intervals of crank angle (θ), preferably at a 90°. It is understood, however, that the ignitions may not be performed at predetermined intervals but a plurality of (two) cylinders may be ignited almost simultaneously. - Exhaust flows 18 are discharged sequentially from the
cylinders 27 through theexhaust manifold 47 in the same order as thecylinders 27 are ignited. When theengine 11 is in a normal operating state such as at full load, the pressure of theexhaust 18 can be relatively high and the amount of theexhaust 18 can be relatively large. Thus, most of theexhaust 18 can be discharged into thewater 2 against water pressure through theexhaust passage 48 of theexhaust manifold 47. A small amount of the rest of theexhaust 18 can be discharged to the ambient atmosphere through the idlingexhaust passage 57. The rotation (R) of thecrankshaft 22 by the operation of the engine drives thepropeller 10 via thepower transmission apparatus 12 to thereby propel thewatercraft 1. - When the
engine 11 is idle, the pressure of theexhaust 18 can be relatively low and the amount of the exhaust can be relatively small. Thus, due to water pressure, theexhaust 18 can be prevented from being discharged into thewater 2 through theexhaust passage 48 of theexhaust manifold 47, and thus most of theexhaust 18 can be discharged to the ambient atmosphere through the idlingexhaust passage 57. - Referring to
FIGS. 1, 4 and 8, regulatingparts 78 can be formed at the downstream ends of the respectivemidway exhaust pipes 50, or midway parts of theexhaust passage 48 thereof The opening of the regulatingparts 78 can be made variable by a plurality of (four)butterfly regulating valves 79 individually provided at the downstream ends of themidway exhaust pipes 50. The regulatingvalves 79 can be operatively connected to each other to selectively open and close together. An actuator (not shown) can be provided for moving the regulating valves. It is understood that the regulatingvalves 79 may be moved individually. - With the above structure, the
exhaust manifold 47 includes the first to eighthupstream exhaust pipes 49A to 49H extending respectively from the first toeighth cylinders 27A to 27H. The first to fourthmidway exhaust pipes 50A to 50D extend respectively from a joined portion of the extended ends of the first and fifthupstream exhaust pipes upstream exhaust pipes upstream exhaust pipes upstream exhaust pipes downstream exhaust pipes midway exhaust pipes midway exhaust pipes - As a result, an
exhaust 18 from thefirst cylinder 27A, for example, flows sequentially through the firstupstream exhaust pipe 49A, the firstmidway exhaust pipe 50A and the firstdownstream exhaust pipe 51A to the ambient atmosphere. Next, anexhaust 18 from thesecond cylinder 27B flows sequentially through the secondupstream exhaust pipe 49B, the secondmidway exhaust pipe 50B and the seconddownstream exhaust pipe 51B to the ambient atmosphere. Next, anexhaust 18 can be discharged from thethird cylinder 27C. Thisexhaust 18 will be discussed in greater detail below. Next, anexhaust 18 from thefourth cylinder 27D flows sequentially through the fourthupstream exhaust pipe 49D, the fourthmidway exhaust pipe 50D and the seconddownstream exhaust pipe 51B to the ambient atmosphere. Thus, the subsequent pulses ofexhaust 18 discharged from thesecond cylinder 27B and thefourth cylinder 27D can be prevented from interfering with theexhaust 18 from thefirst cylinder 27A in theupstream exhaust pipes 49, themidway exhaust pipes 50 and thedownstream exhaust pipes 51. - The
exhaust 18 from thethird cylinder 27C described above flows sequentially through the thirdupstream exhaust pipe 49C, the thirdmidway exhaust pipe 50C and the firstdownstream exhaust pipe 51A to the ambient atmosphere. Thus, both theexhaust 18 from thefirst cylinder 27A and theexhaust 18 from thethird cylinder 27C flow through the firstdownstream exhaust pipe 51A. Accordingly, theexhaust 18 from thethird cylinder 27C may interfere with theexhaust 18 from thefirst cylinder 27A in the firstdownstream exhaust pipe 51A. - Advantageously, the first
upstream exhaust pipe 49A and the firstmidway exhaust pipe 50A, through which theexhaust 18 from thefirst cylinder 27A flows, and the thirdupstream exhaust pipe 49C and the thirdmidway exhaust pipe 50C, through which theexhaust 18 from thethird cylinder 27C flows, can be separate from each other and have a relatively long length. For this reason, the first andthird cylinders first exhaust passage 48. Thus, theexhaust 18 from thethird cylinder 27C can be prevented from interfering with theexhaust 18 from thefirst cylinder 27A in the firstdownstream exhaust pipe 51A. - The
first cylinder 27A and thefifth cylinder 27E can be positioned in proximity to each other because the first and fifthupstream exhaust pipes first cylinder 27A and thefifth cylinder 27E, can be joined to each other. However, the ignition interval between thefirst cylinder 27A and thefifth cylinder 27E can be significantly long due to ignitions of the second tofourth cylinders 27B to 27D occurring therebetween. As a result, overlapping of the exhaust strokes of thefirst cylinder 27A and thefifth cylinder 27E can be prevented. Thus, theexhaust 18 from thefifth cylinder 27E can be prevented from interfering with theexhaust 18 from thefirst cylinder 27A in the first and fifthupstream exhaust pipes - The interval between ignition of the
first cylinder 27A and ignitions of the sixth toeighth cylinders 27F to 27H can be even longer. As a result, theexhausts 18 from the sixth toeighth cylinders 27F to 27H can be prevented from interfering with theexhaust 18 from thefirst cylinder 27A. - The above description of the
exhaust 18 from thefirst cylinder 27A can apply to theexhaust 18 from theother cylinders 27. As a result, interference of the exhaust pulses in theengine 11 can be prevented, and thus desired exhaust pulses having a sufficiently high negative pressure can be obtained. Therefore, the enhanced performance of theengine 11 can be achieved more reliably. - As described above, each pair of the first and fifth
upstream exhaust pipes upstream exhaust pipes upstream exhaust pipes upstream exhaust pipes - Of the
exhausts 18 from the first toeighth cylinders 27A to 27H, the following can be more likely to interfere with each other: theexhausts 18 from the first andfifth cylinders upstream exhaust pipes exhausts 18 from the second andsixth cylinders upstream exhaust pipes exhausts 18 from the third andseventh cylinders upstream exhaust pipes exhausts 18 from the fourth andeighth cylinders upstream exhaust pipes - Therefore, as described above, the first and fifth
upstream exhaust pipes - As a result, interference of
exhaust 18 from thefirst cylinder 27A with anexhaust 18 from thefifth cylinder 27E ignited fourth after thefirst cylinder 27A and interference of theexhaust 18 from thefifth cylinder 27E with anexhaust 18 from thefirst cylinder 27A ignited fourth after thefifth cylinder 27E can be set to about the same level. That is, interference between theexhausts 18 from the first andfifth cylinders - As described above, the
engine 11 having the plurality ofcylinders 27, the firstexpansion chamber case 56A for collecting therein exhausts 18 from the first part of thecylinders 27, and the secondexpansion chamber case 56B for collecting therein exhausts 18 from the second part of thecylinders 27 can be provided. The first andsecond exhaust passages expansion chamber cases water 2 at thedownstream end openings 48 a to 48 d. - As a result, when the
exhaust 18 from somecylinders cylinders 27 and theexhaust 18 from theother cylinders expansion chamber cases water 2 through the first andsecond exhaust passages respective exhausts 18 can be prevented more reliably. As a result, interference of the exhausts in theengine 11 can be prevented effectively, and thus desired exhaust pulses having a sufficiently high negative pressure can be obtained. The enhanced performance of theengine 11 can be thereby achieved more reliably. - As described above, of the
cylinders 27, thecylinders cylinders 27, and thecylinders cylinders 27. - Incidentally, the
exhaust 18 from the cylinders ignited in odd-numbered (or even-numbered) order can be most significantly interfered with thesubsequent exhausts 18 from the cylinders ignited in even-numbered (or odd-numbered) order. - Thus, in some embodiments, the pulses of
exhaust 18 from thecylinders 27 ignited in odd-numbered order and the pulses ofexhaust 18 from thecylinders 27 ignited in even-numbered order can be discharged individually into thewater 2. As such, of interferences of the pulses ofexhaust 18, maximum possible interference can be prevented, and the enhanced performance of the engine can be achieved effectively. - As described above, the
downstream end openings second exhaust passages case 9 below thesurface 2 a of thewater 2. Thepartition 52 can be provided extending in the longitudinal direction of thehull 3 to separate thepropeller 10 and thedownstream end openings case 9. - As a result, when the
exhaust 18 from thecylinders 27 is discharged into thewater 2 through thedownstream end openings exhaust 18 can be prevented from flowing toward thepropeller 10. Thus, cavitation that might occur around thepropeller 10 due to theexhaust 18 can be prevented. - As described above, the
water guide 53 can be positioned above thedownstream end openings second exhaust passages partition 52 in a vertical direction, extending generally parallel to thepartition 52 and can be supported by thecase 9. - As a result, when the
watercraft 1 is driven forward by theoutboard motor 4, theexhausts 18 from thecylinders 27 are discharged into thewater 2 through thedownstream end openings exhaust 18 can be carried farther away from thewatercraft 1 in the rearward direction by the water flowing rearwardly along thewater passages 54 between thepartition 52 and thewater guide 53. Then, theexhausts 18 come up from thewater 2 to be released into the ambient atmosphere. - Accordingly, the
downstream end openings surface 2 a of thewater 2 as compared to the case where thedownstream end openings case 9. In this case, however, theexhausts 18 discharged into thewater 2 through thedownstream end openings watercraft 1 can be reduced advantageously. - It is understood that the above description is based on the illustrated example; however, the
engine 11 may be a four-cylinder or six-cylinder engine. It is also understood that thebanks downstream end openings 48 a to 48 d in thecase 9 can be only the lower or upper downstream end openings. - FIGS. 11 to 21 illustrate modifications of the exhaust systems and engines described above with reference to
FIGS. 1-10 . The modifications described below can have many parts, components, and methods of use in common with the exhaust systems and engines ofFIGS. 1-10 . Therefore, those parts and components are identified with the same reference numerals in the drawings and their description, as well as a description of a method if use, is not repeated. Their optional differences, however, are described below. The configurations of the parts and components described above can be combined with the modifications described below in various ways. - Referring to FIGS. 11 to 14, one (left)
bank 24 of thebanks fifth cylinders bank 25 can be formed by the second, fourth, eighth andsixth cylinders - The first, third, seventh and fifth
upstream exhaust pipes midway exhaust pipes downstream exhaust pipe 51A, which can be associated with the first, third, seventh andfifth cylinders crankshaft 22. The other exhaust pipes associated with the second, fourth, eighth andsixth cylinders crankshaft 22. - The
exhaust passage 48 of eachmidway exhaust pipe 50 can have a plurality of (two)catalysts catalysts exhaust 18. Thecatalysts exhaust passage 48. - Of the first and second secondary airs 63, 64, the second
secondary air 64 supplied to the downstream side of thefirst exhaust passage 48 can be supplied to a part of thefirst exhaust passage 48 between thecatalysts second air passage 67 and thereed valve 68. Both the O2 sensors 72, 73 can be disposed downstream of thecatalysts - With the above structure, the
catalysts exhaust passage 48 in theexhaust manifold 47. Thefirst air passage 65 can be formed for supplying firstsecondary air 63 to the upstream side of thecatalysts exhaust passage 48. - As described above, since exhaust pulses having a sufficiently high negative pressure can be obtained, first and second
secondary airs exhaust passage 48 due to the negative pressure. That is, a larger amount of first and second secondary airs 63, 64 can be supplied into theexhaust passage 48. Thus, even when the air-fuel ratio (A/F) of the mixture to be supplied to theengine body 15 of theengine 11 by theintake device 17 is small (rich), the exhaust air-fuel ratio on the upstream side of thecatalysts exhaust 18 can be thereby achieved. That is, as a result of such purification ofexhaust 18, the enhanced performance of theengine 11 can be achieved more reliably. - As described above, the
catalysts exhaust passage 48. - In some embodiments, the
above engine 11 can be incorporated in theoutboard motor 4. Compared to the case where theengine 11 is incorporated in a commercially available automobile, theengine 11 incorporated into an outboard motor will often be operated at a maximum output point under full load. As a result, the flow speed ofexhaust 18 in theexhaust passage 48 becomes relatively high. Thus, in such embodiments, thecatalysts exhaust 18 is exposed to thecatalysts exhaust 18 can be achieved. That is, the enhanced performance of theengine 11 can be achieved more reliably. - It is understood that the
midway exhaust passages 50 may be shorter in length as indicated by chain double-dashed lines inFIG. 11 . - With regard to the modifications illustrated in FIGS. 15 to 21, the engine and exhaust systems therein can be essentially the same as that of
FIGS. 11-14 except that generally theentire exhaust device 19 is arranged in front of theengine body 15. Additionally, balancers 82 can be operatively connected to thecrankshaft 22. - The idling
exhaust passage 57 can be formed for communicating longitudinal “midway parts” of theexhaust passage 48 in themidway exhaust pipes 50 to the ambient atmosphere above the surface of thewater 2. The regulatingpart 78 having the regulatingvalve 79 to vary its opening can be provided on the downstream side of and in proximity to the “midway part” of theexhaust passage 48. - With the above structure, firstly, proper adjustment of the opening of the regulating
part 78 according to the operating state of theengine 11 allows the pressure of theexhaust 18 flowing through themidway exhaust pipe 50 to be reversed by the regulatingpart 78, so that exhaust pulses having a desired negative pressure can be obtained at desired timing. Thus, the more enhanced performance of theengine 11 can be provided. - Secondly, the following operation and effect can be obtained. When the
hull 3 is driven rearward in response to the operation of theswitching device 14 of thepower transmission apparatus 12 in theoutboard motor 4, thewater 2 may flow back through theexhaust passage 48 of thedownstream exhaust pipe 51 and enter the idlingexhaust passage 57, due to the dynamic pressure of thewater 2. In this case, since both theexhaust passages engine 11 may lose speed or stop. - Thus, in response to the operation of the
switching device 14 to drive thehull 3 rearward, if automatic control, manual operation or the like is performed to close the regulatingvalve 79 to decrease the opening of the regulatingpart 78, the entry of thewater 2 into the idlingexhaust passage 57 can be prevented by the regulatingpart 78. Thus, the flow ofexhaust 18 at least through the idlingexhaust passage 57 can be ensured. As a result, theengine 11 can be prevented from losing speed or stopping due to backflow of thewater 2 through theexhaust passage 48. Advantageously, the stable operation of theengine 11 can be continuously effected. - Although these inventions have been disclosed in the context of certain preferred embodiments and examples, it will be understood by those skilled in the art that the present inventions extend beyond the specifically disclosed embodiments to other alternative embodiments and/or uses of the inventions and obvious modifications and equivalents thereof. In addition, while several variations of the inventions have been shown and described in detail, other modifications, which are within the scope of these inventions, will be readily apparent to those of skill in the art based upon this disclosure. It is also contemplated that various combination or sub-combinations of the specific features and aspects of the embodiments may be made and still fall within the scope of the inventions. It should be understood that various features and aspects of the disclosed embodiments can be combined with or substituted for one another in order to form varying modes of the disclosed inventions. Thus, it is intended that the scope of at least some of the present inventions herein disclosed should not be limited by the particular disclosed embodiments described above.
Claims (12)
Applications Claiming Priority (2)
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JPJP2006-204700 | 2006-07-27 | ||
JP2006204700A JP2008031898A (en) | 2006-07-27 | 2006-07-27 | Exhaust system in outboard motor |
Publications (2)
Publication Number | Publication Date |
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US20080026654A1 true US20080026654A1 (en) | 2008-01-31 |
US7556548B2 US7556548B2 (en) | 2009-07-07 |
Family
ID=38986894
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Application Number | Title | Priority Date | Filing Date |
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US11/829,499 Expired - Fee Related US7556548B2 (en) | 2006-07-27 | 2007-07-27 | Exhaust device for outboard motor |
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US (1) | US7556548B2 (en) |
JP (1) | JP2008031898A (en) |
Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20070240410A1 (en) * | 2006-04-17 | 2007-10-18 | Yoshibumi Iwata | Multiple-cylinder engine for outboard motor |
US20080020659A1 (en) * | 2006-04-14 | 2008-01-24 | Kentaro Kameoka | Idle exhaust structure for outboard motor |
US20130280970A1 (en) * | 2012-04-11 | 2013-10-24 | Brunswick Corporation | Marine propulsion systems, intake air systems for marine propulsion systems, and marine propulsion systems having exhaust gas relief outlet |
US20140057508A1 (en) * | 2012-08-24 | 2014-02-27 | Brunswick Corporation | Marine propulsion systems having exhaust gas relief outlet |
US8858282B2 (en) | 2012-04-11 | 2014-10-14 | Brunswick Corporation | Marine propulsion systems and intake air systems for marine propulsion systems |
US8978372B2 (en) | 2013-02-25 | 2015-03-17 | Yamaha Hatsudoki Kabushiki Kaisha | V-type engine, outboard motor, and vessle |
Families Citing this family (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2008031898A (en) * | 2006-07-27 | 2008-02-14 | Yamaha Marine Co Ltd | Exhaust system in outboard motor |
US9903251B1 (en) | 2011-11-29 | 2018-02-27 | Brunswick Corporation | Outboard motors and exhaust systems for outboard motors having an exhaust conduit supported inside the V-shape |
US9174818B1 (en) | 2011-11-29 | 2015-11-03 | Brunswick Corporation | Marine engines and exhaust systems for marine engines having a catalyst for treating exhaust |
US9758228B1 (en) | 2016-07-01 | 2017-09-12 | Brunswick Corporation | Exhaust manifolds for outboard marine engines |
US10329978B1 (en) | 2018-02-13 | 2019-06-25 | Brunswick Corporation | High temperature exhaust systems for marine propulsion devices |
US10995648B1 (en) * | 2018-03-27 | 2021-05-04 | Brunswick Corporation | Marine drives having a muffler for tertiary exhaust outlet |
WO2020166151A1 (en) * | 2019-02-13 | 2020-08-20 | 本田技研工業株式会社 | Outboard motor |
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US3127866A (en) * | 1962-04-27 | 1964-04-07 | Outboard Marine Corp | Outboard motor mounting arrangement |
US3431882A (en) * | 1967-03-26 | 1969-03-11 | Outboard Marine Corp | Marine propulsion device |
US4881370A (en) * | 1987-02-10 | 1989-11-21 | Sanshin Kogyo Kabushiki Kaisha | Exhaust device for outboard motor |
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JP3630004B2 (en) | 1999-03-11 | 2005-03-16 | スズキ株式会社 | Outboard motor exhaust passage structure |
JP2008031898A (en) * | 2006-07-27 | 2008-02-14 | Yamaha Marine Co Ltd | Exhaust system in outboard motor |
-
2006
- 2006-07-27 JP JP2006204700A patent/JP2008031898A/en not_active Withdrawn
-
2007
- 2007-07-27 US US11/829,499 patent/US7556548B2/en not_active Expired - Fee Related
Patent Citations (3)
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US3127866A (en) * | 1962-04-27 | 1964-04-07 | Outboard Marine Corp | Outboard motor mounting arrangement |
US3431882A (en) * | 1967-03-26 | 1969-03-11 | Outboard Marine Corp | Marine propulsion device |
US4881370A (en) * | 1987-02-10 | 1989-11-21 | Sanshin Kogyo Kabushiki Kaisha | Exhaust device for outboard motor |
Cited By (10)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20080020659A1 (en) * | 2006-04-14 | 2008-01-24 | Kentaro Kameoka | Idle exhaust structure for outboard motor |
US7513811B2 (en) | 2006-04-14 | 2009-04-07 | Yamaha Hatsudoki Kabushiki Kaisha | Idle exhaust structure for outboard motor |
US20070240410A1 (en) * | 2006-04-17 | 2007-10-18 | Yoshibumi Iwata | Multiple-cylinder engine for outboard motor |
US7523735B2 (en) * | 2006-04-17 | 2009-04-28 | Yamaha Hatsudoki Kabushiki Kaisha | Multiple-cylinder engine for outboard motor |
US20130280970A1 (en) * | 2012-04-11 | 2013-10-24 | Brunswick Corporation | Marine propulsion systems, intake air systems for marine propulsion systems, and marine propulsion systems having exhaust gas relief outlet |
US8858282B2 (en) | 2012-04-11 | 2014-10-14 | Brunswick Corporation | Marine propulsion systems and intake air systems for marine propulsion systems |
US20140057508A1 (en) * | 2012-08-24 | 2014-02-27 | Brunswick Corporation | Marine propulsion systems having exhaust gas relief outlet |
WO2014031180A1 (en) * | 2012-08-24 | 2014-02-27 | Brunswick Corporation | Marine propulsion systems having exhaust gas relief outlet |
US9051041B2 (en) * | 2012-08-24 | 2015-06-09 | Brunswick Corporation | Marine propulsion systems having exhaust gas relief outlet |
US8978372B2 (en) | 2013-02-25 | 2015-03-17 | Yamaha Hatsudoki Kabushiki Kaisha | V-type engine, outboard motor, and vessle |
Also Published As
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US7556548B2 (en) | 2009-07-07 |
JP2008031898A (en) | 2008-02-14 |
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